TextBoxes not Updating after Switching Views in an MVVM Appliation

I am not sure if this is a Prism, Unity Injection or WPF question or if this is the correct forum for my question. It is posted here and on the MSDN WPF forum.

My application switches views from different modules into a "workspace" region via command buttons. One button causes the display of textboxes in a TabControl which are dynamically updated as the user navigates a ListBox which is in the "navigation"
region. This works perfectly until the user clicks a command button to display different views in the navigation and workspace regions. When the user then clicks the command button which, again, injects the ListBox and TabControl into the regions, my textboxes
are no longer updated when the user navigates the ListBox.

I sat breakpoints to check the C# code that does the updating of the textboxes. It seems to work perfectly, but the strings are not displayed in the textbox controls on the TabControl